FIREFIGHTERS have saved a $US450 million NASA satellite and US taxpayers more than $US1 billion which would have been spent to replace the satellite.

Washington volunteer firefighters were called out to the Naval Research Laboratory at 1pm yesterday to extinguish an outside fire.

Dvids.net reports that the firefighters found fire and smoke coming from a tractor-trailer truck which was transporting the $US450 million ($490 million) NASA Magnetospheric Multiscale Satellite from NASA's Goddard Space Flight Centre in Maryland.

Luckily the satellite was saved from damage and then promptly boxed, double wrapped and sent to Maryland ahead of its launch into space late next year.

A NASA spokesman said the spacecraft would go through a series of tests before take off.

He said so far the satellite appears to be fine.

The satellite, one of four set to launch, will investigate how the sun and Earth's magnetic fields connect and disconnect, transferring energy from one to the other – a fundamental physical process that is known as magnetic reconnection.